Method of polymerizing rosin



' Patented Feb. 22, 1944 uNlTsD nunon oli*` ronnmarzma vnosnv,

ClcllE.

` Tyler, Hattiesburg, Hhs.,

`Pluriel' (Ja-any. a corporation of Dehware i passim my 4, mz, so. 44ams (ci. rsasn This invention relates to an improved con tinuliousy methodfor the polymerization of rosin. In my' copending application. SerialNo. 328,-

led A111110, 1940, 110W U. S. Patent N.

2,281,659, a process h disclosed for polymerizing rosin involving use asa polymerization catalyst of an acid sludge formed by treatment of rosinwith sulfuric acid. I have now discovered an improvement over mypreviously described`proc easl which provides more rapid polymerizationwith use of less sulfuric acid. The improved process is entirelycontinuous and provides a polymerized rosin with very little drop inacid num-y It is well `known that on subjecting rosin to polymerizingconditions in contact with various polymerization catalysts only a loworder of polymerization occurs. The polymerization does not appear toproceed beyond the dimer stage. The dimer of a rosin ot melting point of80 C. has a melting point oi` approximately F75-180 C. Polymerized rosinthus has become generally known in the art as a mixture ot the dimer andunpolymerized rosin. The polymerized rosin, therefore, contains varyingproportions of the dimer and thcunpolymerized rosin, depending on thedegree of polymerization involved as indicated by the melting point, forexample: The dimer is considered to be substantially completelypolymerized rosin. y

The improved polymerization process described inaccordance with thisinvention involves continuouslycontacting asolution of a mixture ofsubstantially completely polymerized rosin and substantiallyunpolymerized rosin in a suitable solvent at a temperature `within therange of about ,-10 to about65 C. with sulfuric acid of a concentrationfrom about 65% to about 102% and in amount within the range o! about toabout 50% lby weight of the above polymerized and unpolymerized rosinmixture undercondiv tions oi reaction adapted to effect polymerizationof the unpolymerilcd rosin contained in the above solution, therebycausing the separation oi an acid sludge layer which is insoluble in thesolvent and which comprises an association product o! the sulfuric acidand the mixture of unpolymerixed rosin and completely polymerized rosin.A separation is then elected between the separated acid sludge layer andthe solution layer. The solution layer contains the substantiallycompletely polymerized rosin in a higher proportion than present in theoriginal solution and is washed with water until substantially free ofacid and the solvent evaporated to tree the desired poly# merizedrosin;` '111e sludge layer' is brought into contact with a solution ofunpolymeriled rosin in a suitablelaolvent 'at a tempa'ature of about-"C1. toabout 65 O. and auch contact `ini is out for arsumcient time toeilect substantialpolymeriaationoltberoain. Thelolution o! partiallyplymerized rosin. is from the acidsludlelayerandisrecycledtothenrststep'oitheproceaa Tbeacidaluckelayer which is separated. at thispoint is either recycled to the step involving contacting oi acid sludgewith the solution of unpolymeriaed rosin, or is brought into contactwith a fresh amount of unpolymerized rosinisolution. or it is removedfrom the system. Each of the above steps ot the process is carried outinl a continuous manner so that a continuous ilow of materials takesplace and a solution of polymerized rosin representinz the desireddegree of polymerization is delivered continuously from the operation.The system requires no interruption and is capable or very close andaccurate control.

The ilow sheet diagram illustrates the flow'of materials in accordancewith the process of the invention. "Ihe particular form of apparatus tobe used'in carrying outV the process is not critical. A convenient formo! apparatus which has been found to be very desirable consists of apair of lpolymerizingvessels connected in series with each other.` Inthe ilrst oi such a pair of polymerizing vessels the step of contactingthe solution of the mixture of completely polymerized rosin andunpolymerized rosin with sulfuric acid is carried out, while in thesecond polymerizing vessel the contacting oi the separated acid sludgefrom the ilrst polymerizing vessel with the solution of unpolymerizedrosin is carried out. In such a system. the ilnished polymerized rosinsolution nows from the second of the pair of polymerizing vessls whilethe unpolymerized rosin solution enters the first polymerizlng vessel.

Example I to permit rosin solution to enter the bottom oi.'

.the ilrst'poiymerizer and sulfuric acid at the topcof the secondpolymerizer. Before starting the operation, each polymerizer was filledwith a 50% solution in benzol of a partially polymericed M wood rosinand an acid sludge produced by reaction oi 95.5% sulfuric acid on a 50%.solution of lvl wood rosin in benzol. The ratio oi acid sludge topartially polymerized rosin solution introduced into the polymer-12erswas 15%. The operation was then carried out by pumping a 50% solution ofM wood rosin in benzol into the'bottom of the iirst polymerizer at alrate of 184 lbs. per houx and 95.5% sulfuric acid into the top of thesecond polymerizer at a rate of 14 lbs. per hour. The temperature or'contacting in each polymerizer was-maintained at 1517 C. The ratio ofacid sludge to rosin solution in each polymerizer during the operationwas held constant at about 12 to 15%. The polymerized rosin solutionflowing out of the second polymerizer was washed to remove residual acidand the solvent evaporated to give the nnished polymerized rosin. Thepolymerized rosin obtained on the abovebasis had the following analysis:

original M Polymerase wood rosin rosin Acid No i60 160. Melting point(drop) 82 C 100 C. Color M Ito K. I

Benning of the polymerized rosin obtained by. heating at 270 C. for 30minutes improved the color to 23 Amber (WG grade) and removed alltr'aces of residual sulfur.

Example II solution ilowing outA of thesecond polymerizer andevaporation ot the solvent had the following analysis in comparison tothe original rosin:

Original Polymerized gum rosin rosin (d. e Color po op K K.

The rosin which may be polymerized in accord'- ance with the method of.this invention may be any of the various grades of Wood or gum rosin.It may have been previously heat-treated, distilled or'rei'lned' by anyoi they processes known to the art. The crystalline rosin acids may alsobe used if desired. When treating wood rosin,

.a rosin is preferred which has been subjected to a rening operation forthe removal of color bodies, although unrened wood rosin may be treatedaccording to the process. Any of the usual grades of gum rosin are welladapted for treatment by the process. yRosins which have beenheat-treated prior to introduction in the process will, in general.givenv a polymerized rosin of higher melting point than obtainable fromthe corresponding rosin which has not been heat-treated.

The concentration of the mixture of completely polymerized rosin andunpolymerized rosin in 'the solution used. the contacting iuris acid asweil es concentration. l lution of nnpolyraericed rosin contacted, withthe acid sludge catalyst may vary over the range of about i0% to about60% by weight and prei erably will be within the range of from about 25%to about 55% by weight. Among the solvents for rosin which may be usedare coal tar hydrocarbons, as for example, benzol, toluol, xylol;petroleum hydrocarbons. as for example, pentane, hexane, heptane, andvarious gasoline fractions, such as those boiling within the range fromabout C. to about 175 C.; hydrogenated petroleum solvents, such as thoseknown under the trade name of Solvesso; carbon tetrachloride,dichlorobutane, monochlorbenzene; cyclohexane, para-menthane,decahydronaphthalene, etc. The solvent used will be one in which theracid sludge catalyst is substantially insoluble.

Oi the solvents mentioned, benzol and the gasoline fractions are mostreferred.

Referring to the :do sheet, the sulfuric acid used to contact the s tionof a mixture of cornpletely polymerlzed rosin and unpolymeriaed rosinmay vary within the range of about 65% to about 10,2%, and preferablywill be within the range 65 C. and preferably will fall within the rangeof about 0 C. to about 25 C. At'temperatures above about 25 C. slightreactions occur which tend to darken the rosin, while at temperaturesbelow about 0 C. the viscosity of the sludge is greatly increased andthe polymerization reaction proceeds much more slowly.

As will be apparent from the description of the process, the acid sludgecatalyet is free-flowing in nature and thus is handled as a heavyliquid. The concentration of therosin in the solvent and the particularsolvent employed have some effect on theviscosity of the acid sludge.The concentration of the sulfuric acid also exerts an effect on thefluidity of the acid sludge. By suitable control of the rosin solutionconcentration, the strength of sulfuric acid and the temperature ofcontacting, it will be possible to maintain the conditions *so as toprovide a free-flowing acid sludge and thus facilitate the carrying outof the process.

The contacting oi Ythe solution of unpolymerized rosin with the acidsludgelayr separated from the rst contacting step may likewise becarried out at temperatures'within the range of about 10 C.V to about 65C. and preferably from about 0 C. to about 25 C. The ratio of acidsludge to the unpolymerized rosin solution may be varied from about 5%to about 95%, while a preferable ratio will be about-12% to about 40% byweight. 'I'he concentration of unpolymerized rosin in the solutioncontacted with the acid sludge may vary over the range of about 10% toabout 60% by weight, and preferably will be within the range of fromabout 25% to about 55% by weight. The time of contacting theunpolymerized rosin solution with the acid sludge catalyst will dependon the temperature of contacting and particularly on the concentrationof sulfuric acid used'in preparing the acid sludge.

The solution or partially polymerized rosin attacca containing a mixtureof completely polymerized rosin'und unpolymerized rosin which isobtained as a result ci the contacting of the unpolymerized rosinsolution with theacid sludge catalyst. is separated from the acid sludgelayer and is recycled to the` beginning ofthe process to be contactedwith sulfuric acid, thereby to ellect the production of a new acidsludge. The acid sludge layer separated from the contacting of theunpolymerized rosin solution with the acid sludge catalyst may berecycled and used to treat additional unpolymerized rosin solution, orlt may be removed from the system.` Also, a third polymerizing vesselmay be used where the acid sludge is used to contact more-unpolymerizedrosin solution.` With use of a third polymerzer vessel, higherthroughput of unpolymer- Y ized rosin solution is obtained with a lowerconsumption of sulfuric acid.

By means of the improved process described in accordance with thisinvention the continuous production of polymerized rosin may be carriedout with a high degree ofemciency and vwith production of a consistentlyuniform product. The melting point of the finished product may be variedeasily by controlling the solution concentrations, the acidstrength, thetime oficontact of the unpolymerized rosin solution with the acidsludge, as well as the temperature of contact. The process isparticularly adaptable to smooth and emcient production of polymerizedrosins melting up to about 135 C. In the case of polymerized wood rosin,such a polymerized product contains about 60 to70% of the dimer andabout 30 to 40% of the unpolymerized` rosin. There is practically no`loss of rosin in the process since the acidsludge .catalyst removedfrom the system may be treated to recover the rosin contained in it.Thespent vacid` sludge catalyst usually contains less than about 7% ofthe unpolymerized rosin introduced in the process. The yield of`finished polymerized rosin without recovery oi the rosin contained inthe spent acid sludge is, therefore, usually-,at least about 93% byweight.

The polymerized rosin obtained in the abovedescribed process may besubjected to refining treatment, such as heat 'treatment at 250 to 350C. to remove the small traces o! sulfur, selective solvent refining,treatment with nascent hydrogen, etc. Also, before washing thepolymerized rosin solution, the crude solution may be subjected to ahydrolysis treatment with a strong polybasic mineral `acid `tofacilitate the water washing step, such a hydrolysis procedure beingdescribed in an application of Alfred L. Rummelsburg, Serial No.371,990, filed December 27, 1940, now U. S. Patent No. 2,300,065.

My above-described process of polymerizing rosnls an improvement over mypreviously described method referred to above in several importantrespects. .'I'hus, it requires no interruptions and is entirelycontinuous. It provides faster throughput of vrosin with a given amountof sulfuric acid and thus provides higher yields of polymerized rosinfrom a given weight of sulfuric acid or, ofl acid sludge. Also.

` rosinfin a suitable solvent at a temperature withi. l continuousprocess of polymerizing rosin which includes continuously contacting asolution of a mixture of substantially completely polymerized rosin andsubstantially unpolymerized rosin in a suitable solvent at a temperaturewithin the range of `about -10 C. to about 65 C. with sulfuric acid of aconcentration within the range of about 65% to about 102% and in anamount within the range of about 5% to about by weight ofv the abovepolymerized and unpolymerized rosin mixture under conditions of reactionadapted to effect polymerization of the unpolymerized rosin contained inthe mixture and thereby causing the separation of an acid sludge layercomprising an association product of the sulfuric acid and the mixtureof unpolymerized rosin and completely polymerized rosin which isinsoluble in the said solvent, removing polymerized rosin solutioncontinuously from the separated acid sludge layer, continuouslycontacting the separated acid sludge layer with a solution ofunpolymerized rosin in the same solvent at a temperature in the range ofabout v 10" C. to about 65 C.` to eiect a partial polymerization of thesaid rosin into a mixture of substantially completely polymerized rosinvand substantially unpolymerized rosin, separating the solution of thesaid mixture from the acid sludge catalyst layer and recycling thesolution of the mixture of substantially completely polymerized rosinand substantially unpolyinerized rosin to' the first step of theprocess.

2. A continuous process of polymerizing rosin which includescontinuously contacting a solution of a mixture of substantiallycompletely polymerized rosin `and substantially unpolymerized in therange of about l0 C. to about65 2C.

range of about 80% to about 100% and in'an i amount within the range ofabout 10% to about it is capable of much greater control than the 1previously described process and thus is more 25% by weight of the abovepolymerized and' unpolymerzed rosin mixture under conditions of reactionadapted to effect polymerization of the unpolymerized rosin contained inthe mixture and thereby causing the separation of an acid sludge layercomprising an association product of the sulfuric acid and the mixtureof unpolymerized rosin and completely polymerized rosin which isinsoluble in the said solvent, removing polymerized rosin solutioncontinuously from the separated acid sludge layer, continuouslycontacting the separated acid sludge layer with a solution ofunpolymerized rosin in the same solvent at a temperature in the range ofabout 10 C. to about 65 C. to effect a partial polymerizationl of thesaid rosin into a mixture of substantially completely polymerized rosinand substantially unpolymerized rosin, separating the solution of thesaid mixture from lthe acid sludge catalyst layer and recyclingthesolution of the mixture of substantially completely polymerized rosinand substantially unpolymerized rosin to the first step of the process.y

3. A continuous process of polymerizing rosin i which includescontinuously contacting a solution.

containing about 10 to `about 60% by Weight cfa mixture ofsubstantiallycompletely polymerized rosin and substantially 'unpolymerized rosinin asuitable solvent at a temperature within the range of about fl0 C. toabout 65V C. with sulfuric acid of a concentration within the range ofabout 65% to about 102% and in an amount within the range of about 5% toabout 50% 4by weight of the above polymerized and unpolymerized rosinmixture under conditions of reaction adapted to efiect polymerization ofthe unpolymerized rosin contained in the mixture and thereby causing theseparation of an acid sludge layer` comprising an association product ofthe sulfuric acid and the mixture of unpolymerized rosin and completelypolymerized rosin which is insoluble inthe said solvent, removingpolymerized rosin solution continuously from the separated acid sludgelayer, continuously contacting the separated acid sludge layer with asolution of unpolymerized rosin in the same solvent at a. temperatureinthe range of about -10 C. to about 65 C. to eiect a partialpolymerization of the said rosin into a mixture of substantiallycompletely polymerized rosin and substantially unpolymerized rosin,separating the solution of the said mixture from the acid sludgecatalyst layer and recycling the solutionl of the mixture ofsubstantially completely polymerized rosin and substantiallyunpolymerized rosin to the first step of the process.

4. A continuous process of polymerizing rosn which includes continuouslycontacting a solution containing about 25 to about 55% by weight of amixture of substantially completely polymerized rosin and substantiallyunpolymerized rosin in a suitable solvent at a temperature within theran-ge of about 10 C. to aboutr65 C. with sulfuric acid of aconcentration within the range of about 65% to about 102% and in anamount within the range of about 5% to about 50% by weight of the abovepolymerized and unpolymerized rosin mixture under conditions of reactionadapted to effect `polymerization of the unpolymerized rosin containedin the mixture and thereby causing the separation of an acid sludgelayer comprising an association product of the sulfuric acid and themixture of unpolymerized rosin and completely polymerized rosin which isinsoluble in the said solvent, removing polymerized rosin solutionoontinuously from the separated acid sludge layer, continuouslyVcontacting the separated acid sludge layer with a solution ofunpolymerized rosin in the same solvent at a temperature in the range ofabout 10 C. to about 65 C. to eiecta partial polymerization ofthe saidrosin into a mixture of substantially completely polymerized rosin andsubstantially unpolymerized rosin, separating the solution of the saidmixture from the acid sludge catalyst layer and recycling the solutionof the mixture of substantially completely polymerized rosin andsubstantially unpolymerized rosin to the irststep of the process.

5. A continuous process of polymerizlng rosin which includescontinuously contacting a solution containing about25 to about 55% byweight of a mixture of substantially vcompletely polymerized 'rosin' andsubstantially unpolymerized rosin in a suitable solvent at a temperaturewithin the range ofl about 10 C. to about 65 C. with sulfuric acid of aconcentration within the range of about 80% to about 100% and in anamount Within the range of about 10% to about 25% by Weight of the abovepolymerized and unpolymerized rosin mixture under condiwith a solutionof unpolymerized rosin in the same solvent at a temperature in the rangeof about -10 C. to about 65 C. to eilect a partial polymerization of thesaid rosin into a mixture of substantially completely polymerized rosinand substantially unpolymerized rosin, separating the solution of thesaid mixture from the acid sludge catalyst layer and recycling thesolution of the mixture of substantially completely polymerized rosinand substantially unpolymerized rosin to the iirst step of the process.

6. A continuous process of polymerizing rosin which includescontinuously contacting a solution containingabout 25 to about 55% byweight of a mixture of substantially completely polymerized rosin andsubstantially unpolymerized rosin in a suitable solvent at a temperatureWithin the range of about 0 C. to about 25 C. with sulfuric acid of aconcentration within the range of about 'to about 102% and in an amountwithin the range of about 5% to about 50% by weight of the abovepolymerized and unpolymerized rosin mixture under conditions of reactionadapted to effect polymerization of the unpolymerized rosin contained inthe mixture and thereby causing the separation of an acid sludge layercomprising an association product of the sulfuric acid and the mixtureof unpolymerized rosin and completely polymerized rosin which isinsoluble in the said solvent, removing polymerized rosin solutioncontinuously from the separated acid sludge layer,l continuouslycontacting the separated acid sludge layer with a solution ofunpolymerized rosin in the same solvent at a said rosin into a mixtureof substantially ycompletely polymerized rosin and substantiallyunpolymerized rosin, separating the solution of the said mixture fromthe acid sludge catalyst layer and recycling the.solution of the mixtureof substantially completely polymerized rosin and substantiallyunpolymerized rosin to the first step of the process. f Y y 7. Acontinuous process oi polymerizing rosin which includes continuouslycontacting a solution containing about 25 to about 55% by weight of amixture of substantially completely polymerized rosin and substantiallyunpolymerized rosin in benzol at a temperature Within the range of about10 C. 'to about 65 C. with sulfuric acid of a concentration Within therange of about 65% to about 102% and in an amount within the range ofabout 5% to about 50% by weight of the above polymerized andunpolymerized rosin mixture under conditions of reaction adapted toeiect polymerization of the unpolymerized rosin contained in the mixtureand thereby causing the separation of an acid sludge layer comprising`an association product of the sulfuric acid and the mixture ofunpolymerized rosin and completely polymerized rosin which is insolublein the benzol. removing polymerized rosin solution continuously from theseparated lacid sludge layer, continuously' contacting the separatedacid sludge layer with a solution of about 25% to about 55%unpolymerized rosin in benzol at a temperature in the range of aboutV 10C. to about 65 C. to effect a partial polymerization of the said rosininto a mixture of substantially completely polymerized rosin andsubstantially unpolymerized rosin, separating lthe solution of the saidmixture from the acid sludge catalyst and substantially uupoiymerizedrosin to the iirst step o! the process.

8. A continuous process of polymerizing rosin which includescontinuously contacting a solution containing about 10 to about 60% byweight of a mixtureof substantially completely polymerized rosin andsubstantially unpolymerized rosin in a suitable solvent at a temperaturewithin the range o! about '10 C. to about 65 C. with sulfuric acid of aconcentration within the range of about 65% to about 102% and in anamount within the range of about 5% to about 50% by weight of the abovepolymerized and unpolymerized rosin mixture under conditions of reactionadapted to eiIect polymerization of the unpolymerized rosin contained inthe mixture and thereby causing the separation of an acid sludge layercomprising an association product-oi the sulfuric acid and the mixtureoi unpolymerized rosin and completely polymerized rosin which isinsoluble in the said solvent, removing polymerized rosin solutioncontinuously from the sepan polymerized rosin to the first step of theprocess and recycling the acid sludge catalyst.

CLELL E. TYLER.

